1. Field of the Invention
This invention relates to ultrasonic probes for placement of implements through the surface of a body to be diagnosed or treated, and more particularly to such a probe for accurately positioning said implement during such diagnosis or treatment while observing an objective organ or other part of a body being diagnosed or treated.
2. Description of the Prior Art
Heretofore, diagnosis and treatment involving placement of an implement through the skin of a patient, including accurate placement of needles used therein, have totally relied on the sense and judgment of the operator. However, recently, it has been made possible to carry out the same easily and accurately by attaching the needle or other implement, to an ultrasonic probe which enabled the visualization of the objective organ or other part of the patient.
Since the organ or other part to be diagnosed or treated, varies in a wide range, from those storing liquid substances (e.g. gall bladder) to those of a tubular construction (e.g. biliary duct), and also varied as to size from large to extremely small, the following points are required to be satisfied by an ultrasonic probe used for diagnosis or treatment involving puncture type operation using an implement such as a needle, in order to be capable of inspecting these organs or other parts, in their operating condition.
(1) The ultrasonic image is not lost at part of the puncture hole.
(2) Substantially the entire length of the needle is visible.
(3) The needle can reach the objective organ or part, following the shortest path between the surface and the organ or part.
(4) The probe should be positioned so that the part of the body surface to be punctured is freely observable.
However, disadvantageously, prior art arrangement of such ultrasonic probes were as typically shown in FIGS. 1(a) and 1(b), which depict a needle 2 introduced into the body of a patient from outside of an ultrasonic probe through a guide member 1a, attached to the probe, in a direction perpendicular to the scanning direction of the ultrasonic wave. This prior art arrangement has various disadvantages, such as an image of the entire needle cannot be obtained; the part of the surface of the patient's body to be punctured is not easily observable; and the guide member 1a is closely positioned to the body surface and should be thoroughly disinfected prior to use, but usually is not.
In another conventional construction wherein the ultrasonic beam is caused to be emitted obliquely to the needle by sector scanning of the same beam, it was found that luster became rough at a long distance.
In still another prior art arrangement, wherein the ultrasonic beam was emitted obliquely by driving the ultrasonic probe with time delays, it was apparent that complicated expensive circuits were necessary because of the delayed drive, and that the directivity of the beam deteriorated.
In another prior art arrangement, wherein the needle was introduced into the body from the outside of the probe in a direction parallel with the scanning direction of the ultrasonic beam, it was found that the introduction angle of the needle was excessive and the needle did not take the shortest path from the body surface to the organ or other part being diagnosed or treated.